The present technology relates to a signal processing apparatus and method, a receiving apparatus and method, and a transmitting apparatus and method, and more particularly, to a signal processing apparatus and method, a receiving apparatus and method, and a transmitting apparatus and method which are capable of easily performing a high-accuracy frequency transform.
In the related art, in a receiving apparatus, a transmitting apparatus, or the like, a frequency transform has been performed on a reception signal or a transmission signal using a local oscillation frequency FLO to transform an RF signal into an IF signal or an IF signal into an RF signal (for example, see Ertan Zencir, Numan S. Dogan and Ercument Arvas, “A Low-power CMOS Mixer for Low-IF Receivers”, IEEE Radio and Wireless Conference, 2002, pp. 157-160).
In recent years, with the development of communication technology, it is necessary to control a frequency transform with a high degree of accuracy (with a smaller step size).
As a local oscillating unit providing the local oscillation frequency FLO, for example, an integer-N type (hereinafter, also referred to as an “integer type) phase locked loop (PLL) having a division ratio of an integer has been used.
In order to further reduce a step size ΔFLO of the local oscillation frequency FLO, it is necessary to further reduce a step size ΔFVCO of an oscillation frequency FVCO of a voltage controlled oscillator (VCO) in the PLL, but in the integer-N type PLL, the oscillation frequency FVCO of the VCO can have only an integer multiple of a comparison frequency FREF of the PLL. In other words, in order to further reduce the step size ΔFVCO of the oscillation frequency FVCO of the VCO, it is necessary to reduce the comparison frequency FREF of the PLL.
However, the comparison frequency FREF is a parameter related to a loop characteristic of the PLL and is in a tradeoff relation with the performance. Therefore, when the integer-N type PLL is used as the local oscillating unit, it is likely to be difficult to sufficiently reduce the step size ΔFLO of the local oscillation frequency FLO, and to be difficult to control a frequency transform of a reception signal or a transmission signal with a sufficiently high degree of accuracy.
In this regard, a fractional-N type (hereinafter, also referred to as a “fractional type”) PLL having a division ratio of a fraction has been considered for use as a local oscillating unit.